Derivative of \( \displaystyle 5 x \left(25 x^{2} - 45 x + 27\right) \)
Problem 2.1419 · hard
Differentiate \( \displaystyle f(x) = 5 x \left(25 x^{2} - 45 x + 27\right) \).
- \[ \frac{d}{d x} 5 x \left(25 x^{2} - 45 x + 27\right) \]Start with the derivative of the function.✓ Proved
- \[ = \frac{d}{d x} \left(125 x^{3} - 225 x^{2} + 135 x\right) \]algebraDistribute 5*x into the parentheses.✓ Proved
- \[ = \frac{d}{d x} 135 x - \frac{d}{d x} 225 x^{2} + \frac{d}{d x} 125 x^{3} \]sumApply the sum rule for differentiation.✓ Proved
- \[ = 135 \frac{d}{d x} x - 225 \frac{d}{d x} x^{2} + 125 \frac{d}{d x} x^{3} \]constant-multiplePull out the constant coefficients.✓ Proved
- \[ = 375 x^{2} - 450 x + 135 \]power simplifyApply the power rule to each term. Multiply the constants to get the final result.✓ Proved
Answer \( 15 \left(5 x - 3\right)^{2} \)
Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. The reviewers disagree about how one step is explained; every verdict is in the receipt.
The full receipt
| Line | Status | Checked by | Detail |
|---|---|---|---|
| 1 | ✓ Proved | sympy 1.14.0 | line 1 is the problem as stated |
| 2 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: fail (error) — Step 1 claims to start the differentiation but does not apply the product rule; the derivative of a product must be expanded before the subsequent algebraic steps. The solution skips a required rule application, making the first step incorrect.qwen3.6:27b-mlx: pass
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-10-03gpt-oss:20b: fail (error) 2026-10-03 — Step 1 claims to start the differentiation but does not apply the product rule; the derivative of a product must be expanded before the subsequent algebraic steps. The solution skips a required rule application, making the first step incorrect.qwen3.6:27b-mlx: pass 2026-10-03gpt-oss:20b: pass 2026-10-03
Proved: SymPy reduced the difference between the two sides to zero. Checked independently: a separate
method, named above, confirmed it. Checked numerically: the two sides agree at every sampled point, which is evidence,
not proof. Reviewed: a model or a person read it; that is all a sentence can have. Solution by
gemma4:26b, checked 2026-10-03 with SymPy 1.14.0.